I've had good luck using the reiser filesystem with exim spool
directories because it is very fast when it comes to dealing with
directories with a lot of files. I think it will be even faster than
splitspool.
Patrick von der Hagen wrote:
> Hi all,
>
> I'm trying to run a cluster-setup where a shared filesystem is
> providing a central location for configuration and a common spool to
> several exims.
>
> Basically, a big filesystem is accessed concurrently by three
> mail-servers which would probably be impossible if exim used IPC,
> shared-memory or other "local" means of communication between the
> single exim-processes. However, since exim just does not do that and
> since the filesystem claims to have working locking-mechanisms, this
> sounds like a possible setup.
>
> However, some files, like the hints-databases, might prove to cause
> performace-problems.
>
> So far, I just run exim as queue-only without any queue-runners, in
> order to gather the best-case results. Using three P3-550 with 256MB
> RAM each (certainly no fast setup) I get about 14 mails/second if they
> use the same filesystem but different spool-directories
> (/var/test1/spool, /var/test2/spool, /var/test3/spool). I don't really
> care wheter this is particularly good or bad, given my specific
> hardware. Running the same test on a local harddisk gives me 15
> mails/second, so the remote filesystem doesn't perform too badly.
>
> Now the problem: using the same spool-directory on all servers and no
> other changes, the throughput drops to less than 6 mails/second on my
> servers, giving me a total of about 17 mails/second. One server makes
> 14, three servers get 17.... no scalability at all.
>
> First idea: some locking issue. But what can I do, where can I start
> profiling?
> Second idea: might enablich splitspool help?
>
> Well, splitspool does help. It gets 8,5 mails/second and thus performs
> much better than a normal spool. However, overall performace still is
> not what I had hoped for....
>
> So, please share your advice with poor littel me. ;-)
> Would you suggest that the complete setup is going to go BOOOM and I
> have missed some evil pitfalls?
> Would you think that the performace-problem is exim-related?
> Especially file-locking-related?
> Or would you suggest that my filesystem is causing me headaches, since
> the big impact splitspool has might indicate problems if there are too
> many files in a directory? When I perform my tests I usually send
> several thousand mails, so there tends to be a lot of files in the
> spool....
>
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